1. Field of the Invention
The invention relates to footwear generally and, more particularly, to a walking or sports shoe.
Shoes of the walking or sports type are used in fields such as walking, running on flat or mountainous terrain, skateboarding, ball sports, and the like.
2. Description of Background and other Information
An article of footwear, hereafter “shoe” for convenience, can include a low upper, a high upper, or a mid-height upper. The shoe can also be relatively flexible or, on the contrary, more rigid. However, it is desirable in any case that the shoe sole assembly provide a certain comfort. This means in particular that the sole assembly must dampen forces or the transmission of sensory information related to walking. This also means that the sole assembly must be as lightweight as possible in order to limit the shoe inertia and the fatigue resulting therefrom.
For these reasons, the outer sole assembly, in a number of walking or sports shoes, includes a comfort layer which fulfills a damping role, while conferring a certain lightness to the shoe. However, a comfort layer alone does not necessarily fulfill all of the expected functions of a sole assembly. Indeed, the sole assembly is useful in facilitating walking by means of storing and then releasing at least a portion of the energy generated during foot rolling movement.
To this end, it is known to arrange a reinforcement layer in the sole assembly, so that the comfort layer is located between the upper and the reinforcement layer. The latter, with respect to the simplest sole assemblies, also plays the role of a walking sole. For example, the reinforcement layer can include rubber, a material that improves the grip on the ground. Moreover, the reinforcement layer is capable of storing, and then restoring, at least a portion of the energy generated during the foot rolling movement. Indeed, a rolling movement tensions the reinforcement layer. It is the distance between the upper and the reinforcement layer, i.e., in other words, the thickness of the comfort layer, which enables the tensioning. This tensioning is all the more strong as the comfort layer is thick. At the end of the foot rolling movement, at the moment when the shoe leaves the ground, the energy generated by the tension of the reinforcement layer, namely the walking sole in this case, tends to return the sole assembly to its initial form. It is a spring effect provided to the sole assembly by the walking sole. This effect propels the shoe forward, in the walking direction. The advantage is fatigue reduction for the user, who is required to produce less energy for an equivalent stride.
The benefit of the spring effect, if it occurs, remains however incomplete. For example, there is an inadequate distribution of this effect, in the sense that it is insufficient in certain areas and excessive in others. Moreover, the spring effect is sometimes insufficient in the areas in which it is useful.